SHALLOW-WATER RISSOIFORM GASTROPODS FROM TRISTAN-DA-CUNHA, SOUTH-ATLANTIC OCEAN, WITH RECORDS OF SPECIES FROM GOUGH-ISLAND

Shallow water rissoiform gastropods collected by the Norwegian Scienti fic Expedition (1937-1938) to Tristan da Cunha are described. The faun a consists of Powellisetia cf. philomelae (Watson) (Rissoidae), three new species of Eatoniella, E. trochiformis, E. lineata, and E. tristan ensis (Eatoniellidae), two new species of Onoba, O. crassicordata and O. tristanensis (Rissoidae) and Rissoella cf. irma (Bartsch) (Rissoell idae). A small collection from Gough Island is also described, contain ing three species referred to Onoba, one of which is described as new, O. merelinoides, and a species of Eatoniella. The biogeographic relat ionships of the fauna are briefly discussed.